In recent years, there have been actively made research and development of not only industrial robots but also consumer robots, which play various roles for peoples livelihood. Among such robots, human-like robots (humanoid robot) being able to walk in erect posture are expected to be able to substitute for actions of human beings. In such humanoid robots, many joint parts are provided for imitating actions or motions of a human being, and a variety of motions having a plurality of degrees of freedom in the joint parts are required. For that reason, many actuators for driving joint parts are mounted in an upper half body of a humanoid robot, and the weights thereof become large, so the load to be borne by a support structure for the upper half body is not small.
Here, for example, in a support structure for an upper half body of a robot shown in patent literature 1, a backbone part is stood vertically from a haunch bone part which is supported on two feet. Then, with respect to the backbone part, a horizontal support member extends to the right and left sides of the upper half body at the position of shoulder parts, and arm units of the robot are rotatably mounted on tip ends of the horizontal support member, respectively (see, in particular, FIG. 2A of the patent literature 1). Accordingly, the arm units of the robot will be supported in a state of being hung by the horizontal support member.